For maintaining constant the mixing temperature and/or motor torque on an internal mixer it is known from U.S. Pat. Specification No. 3,447,201 that although both quantities are determined, only the sum of the variations from a predetermined value is converted into a speed change of the drive, both quantities being simultaneously increased or decreased accordingly. This known process has the disadvantage that the two variations cannot be individually minimized.
It is known from German Auslegeschrift No. 20 58 975 to bring about a control of the electrical power of the motor by means of changes to the plunger pressure. However, this control does not lead to constant quality between the individual charges and instead the permitted power is adapted to partial cycles of the mixing process for carbon black or oil addition.
It is known from the Journal KAUTSCHUK UND GUMMIKUNSTSTOFFE, 1971, no. 3, pp. 119 to 127 to bring about a control on the basis of reaction-kinetic data determined from the temperature gradient by means of process computers, the calculation being based on a temperature gradient over a period of time determined by a basic test. The disadvantage of this process is that it is only suitable for checking chemical reactions.
It is known from the Journal Gummi Asbest Kunstatoffe 7/78, 31, pp. 512-515 to carry out a control on the basis of the specific energy. This control has the disadvantage that through maintaining constant this single quantity, variations of other process parameters are increased.